1.3. Specifying the Characteristics of Cable Standards
The cables that connect our networks today have evolved from earlier standards. Although some of these standards are no longer in common use today, understanding them will assist you in appreciating the advantages of the cables that we use today. You should know the characteristics of these standards. In this section, we discuss each of these cable standards in detail.
1.3.1. Critical Information
You should know the speeds, maximum lengths, topology, and cable types associated with each of the main cable standards. In the paragraphs that follow, we discuss each of these characteristics in detail.
1.3.2. 10BASE-T and 10BASE-FL
The most common cable standard used in the early 1990s was 10BASE-T. The "10" represents the maximum speed of 10Mbps; "BASE" represents a baseband type of transmission in which only one signal can be on the wire at any given time; "T" indicates that a twisted-pair cable was used. The maximum length of any network segment using 10BASE-T is 100 meters.
As you can imagine, some organizations needed to have a network segment that was longer than 100 meters. In the mid- to late 1990s, 10BASE-FL was developed to provide the solution. It used a fiber-optic cable to transmit the signal rather than the copper twisted-pair cable. The fiber-optic cable can transmit much further without suffering a loss of signal due to the media itself (a problem referred to as attenuation). The speed of 10BASE-FL was still 10Mbps, but the maximum transmission length could be up to 20 kilometers! Many of these networks are still in use today where speed is not a concern but maximum distance is a factor. Table 1.5 shows the characteristics of 10BASET and 10BASE-FL.
| Speed | Max. Length | Topology | Cable Type | |
|---|---|---|---|---|
| 10BASE-T | 10Mbps | 100 meters | Star | Copper wire Category 3+ |
| 10BASE-FL | 10Mbps | 20 kilometers | Star | Fiber-optic |
1.3.3. 100BASE-TX and 100BASE-FX
100BASE-TX is by far the most common networking standard in use today. The "100" represents the maximum speed of 100Mbps; "BASE" represents a baseband type of transmission; and "TX" represents twisted-pair cable of the type that will support 100Mbps transmission. (We will discuss cable types in greater detail later in this chapter.) Although 100BASE-TX is 10 times faster than 10BASE-T, it is still limited to 100 meters per network segment.
To provide a solution for longer network segments, 100BASE-FX was developed. It uses fiber-optic cable to increase the distance that the signal can be transmitted without suffering from attenuation. Some devices that use 100BASE-FX can transmit up to 20 kilometers! Table 1.6 shows the characteristics of 100BASE-TX and 100BASE-FX.
| Speed | Max. Length | Topology | Cable Type | |
|---|---|---|---|---|
| 100BASE-T | 100Mbps | 100 meters | Star | Copper wire Category 5+ |
| 100BASE-FX | 100Mbps | 20 kilometers | Star | Fiber-optic |
1.3.4. 1000BASE-TX, 1000BASE-CX, 1000BASE-SX, and 1000BASE-LX
The next fastest cable standard is 1000BASEX, Gigabit Ethernet. The "1000" represents 1000Mbps, or 1 Gbps, and "BASE" represents a baseband type of transmission in a star topology. While this standard is implemented in many forms, the only main difference is the cable type used and therefore the maximum distance. Table 1.7 shows the difference in cable types and maximum transmission distance possible for each form of 1000BASEX.
1.3.5. 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER
The newest and fastest cable standard is the 10G standard. As you may have guessed, the 10G standard allows a maximum transmission speed of 10Gbps, or 10 billion bits per second, in a star topology. The 10G standard is currently subdivided into three standards: 10GBASE-SR, 10GBASE-LR, and 10BASE-ER. All of these 10G standards use fiber-optic cable. The major difference between the standards is the maximum transmission distance. Table 1.8 shows the maximum transmission distance for each standard.
| 10GBASE-SR | 10GBASE-LR | 10GBASE-ER | |
|---|---|---|---|
| Maximum Distance | 82 meters | 10 kilometers | 40 kilometers |
1.3.6. Exam Essentials
Recognize the terminology used when identifying cable standards. You should be able to determine the speed and transmission type of a cable standard solely based on its name.
Know the characteristics of the 10BASE-T standard. The 10BASE-T standard indicates a 10Mbps baseband signal that uses a twisted-pair copper wire. This means that the maximum distance for this technology, without the use of repeaters, is 100 meters. 10BASE-T uses a star topology.
List the characteristics of the 10BASE-FL standard. The 10BASE-FL standard indicates a 10Mbps baseband signal that uses a fiber-optic cable. This means that the maximum distance for a run is about 20 kilometers. 10BASE-FL uses a star topology.
Describe the characteristics of the 100BASE-TX standard. The 100BASE-TX standard indicates a 100Mbps (Fast Ethernet) baseband signal that uses a twisted-pair copper cable. This means that the maximum distance for a run is 100 meters, without the use of repeaters. 100BASE-FX uses a star topology.
Know the characteristics of the 100BASE-FX standard. The 100BASE-FX standard indicates a 100Mbps (Fast Ethernet) baseband signal that uses a fiber-optic cable. This means that the maximum distance for a run is 20 kilometers. 100BASE-FX uses a star topology.
Be familiar with the characteristics of the 1000BASE-TX standard. The 1000BASE-TX standard indicates a 1000Mbps (1Gbps) baseband signal that uses unshielded twisted-pair cable. This means that the maximum distance for a run is 100 meters, without the use of repeaters. 1000BASE-TX uses a star topology.
List the characteristics of the 1000BASE-CX standard. The 1000BASE-CX standard indicates a 1000Mbps (1Gbps) baseband signal that uses Category 5 shielded twisted-pair cable. It is therefore more immune to electrical interference, but it has a maximum distance of only 25 meters. 1000BASE-CX uses a star topology.
Describe the characteristics of the 1000BASE-SX standard. The 1000BASE-SX standard indicates a 1000Mbps (1Gbps) baseband signal that uses one fiber-optic cable. This means that it has a maximum distance of 550 meters, without the use of repeaters. 1000BASE-SX uses a star topology.
Know the characteristics of the 1000BASE-LX standard. The 1000BASE-LX standard indicates a 1000Mbps (1Gbps) baseband signal that uses two fiber-optic cables. This means that it has a maximum distance of 5000 meters, with the use of repeaters. 1000BASE-LX uses a star topology.
List the characteristics of the 10GBASE-SR standard. The 10GBASE-SR standard indicates a 10,000Mbps baseband signal that uses fiber-optic cable. Due to the type of fiberoptic cable that it uses, it has a maximum transmission distance of 82 meters. 10GBASE-SR uses a star topology.
Describe the characteristics of the 10GBASE-LR standard. The 10GBASE-LR standard indicates a 10,000Mbps baseband signal that uses fiberoptic cable. Due to the type of fiberoptic cable that it uses, it has a maximum transmission distance of 10 kilometers. 10GBASE-LR uses a star topology.
Know the characteristics of the 10GBASE-ER standard. The 10GBASE-ER standard indicates a 10,000Mbps baseband signal that uses fiberoptic cable. Due to the type of fiberoptic cable that it uses, it has a maximum transmission distance of 40 kilometers. 10GBASE-ER uses a star topology.